Superalloy components, are frequently utilized in extreme environments where they are exposed to a variety of environmentally related damage and wear mechanisms, including: erosion due to impact by high velocity and high temperature airborne particles, high temperature oxidizing and corrosive gases, low-cycle fatigue processes and mechanical abrasion caused by rubbing against other members. The repeated stresses caused by these mechanisms are known to cause cracking and other damage to the components. Because the manufacturing costs for superalloy components are typically relatively high, it is often desirable to repair a damaged or worn component rather than replace it.
Various superalloy materials, such as stainless steels, cobalt base, and nickel base superalloys, used in land-based and aerospace turbine blades and vanes, require special methods to prepare the surface prior to brazing. Conventional processes such as vacuum cleaning, and hydrogen partial pressure cleaning are effective for a wide range of stainless steels, cobalt- and nickel-base alloys. However, vacuum cleaning, and hydrogen partial pressure cleaning are not very effective on alloys containing significant amounts of aluminum and titanium. Nickel based superalloys containing high concentrations of titanium and/or aluminum are very difficult to clean using conventional processes. Titanium and aluminum can oxidize to form complex spinels that penetrate deeply into any existing cracks.